Re: [tpmdd-devel] [PATCH v7 03/10] tpm: fix multiple race conditions in tpm_ppi.c

Traversal of the ACPI device tree was not done right. It should lookup
PPI only under the ACPI device that it is associated. Otherwise, it could
match to a wrong PPI interface if there are two TPM devices in the device
tree.

Removed global ACPI handle and version string from tpm_ppi.c as this
is racy. Instead they should be associated with the chip.

Additionally, added the missing copyright platter to tpm_ppi.c.

Signed-off-by: Jarkko Sakkinen <redacted>
---
  drivers/char/tpm/tpm-chip.c |   4 +-
  drivers/char/tpm/tpm.h      |  16 ++++--
  drivers/char/tpm/tpm_ppi.c  | 136 +++++++++++++++++++++++++++-----------------
  drivers/char/tpm/tpm_tis.c  |  15 +++--
  4 files changed, 108 insertions(+), 63 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index cf3ad24..647867c 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c

@@ -148,7 +148,7 @@ int tpm_chip_register(struct tpm_chip *chip)
  	if (rc)
  		goto del_misc;

-	rc = tpm_add_ppi(&chip->dev->kobj);
+	rc = tpm_add_ppi(chip);
  	if (rc)
  		goto del_sysfs;

@@ -186,7 +186,7 @@ void tpm_chip_unregister(struct tpm_chip *chip)
  	synchronize_rcu();

  	tpm_sysfs_del_device(chip);
-	tpm_remove_ppi(&chip->dev->kobj);
+	tpm_remove_ppi(chip);

  	if (chip->bios_dir)
  		tpm_bios_log_teardown(chip->bios_dir);

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 9880681..69f4003 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h

@@ -27,6 +27,7 @@
  #include <linux/platform_device.h>
  #include <linux/io.h>
  #include <linux/tpm.h>
+#include <linux/acpi.h>

  enum tpm_const {
  	TPM_MINOR = 224,	/* officially assigned */

@@ -94,6 +95,8 @@ struct tpm_vendor_specific {
  #define TPM_VID_WINBOND  0x1050
  #define TPM_VID_STM      0x104A

+#define TPM_PPI_VERSION_LEN		3
+
  struct tpm_chip {
  	struct device *dev;	/* Device stuff */
  	const struct tpm_class_ops *ops;

@@ -109,6 +112,11 @@ struct tpm_chip {

  	struct dentry **bios_dir;

+#ifdef CONFIG_ACPI
+	acpi_handle acpi_dev_handle;
+	char ppi_version[TPM_PPI_VERSION_LEN + 1];
+#endif /* CONFIG_ACPI */
+
  	struct list_head list;
  };

@@ -340,15 +348,15 @@ void tpm_sysfs_del_device(struct tpm_chip *chip);
  int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);

  #ifdef CONFIG_ACPI
-extern int tpm_add_ppi(struct kobject *);
-extern void tpm_remove_ppi(struct kobject *);
+extern int tpm_add_ppi(struct tpm_chip *chip);
+extern void tpm_remove_ppi(struct tpm_chip *chip);
  #else
-static inline int tpm_add_ppi(struct kobject *parent)
+static inline int tpm_add_ppi(struct tpm_chip *chip)
  {
  	return 0;
  }

-static inline void tpm_remove_ppi(struct kobject *parent)
+static inline void tpm_remove_ppi(struct tpm_chip *chip)
  {
  }
  #endif

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 61dcc80..6acdb17 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c

@@ -1,3 +1,22 @@
+/*
+ * Copyright (C) 2012-2014 Intel Corporation
+ *
+ * Authors:
+ * Xiaoyan Zhang <xiaoyan.zhang@intel.com>
+ * Jiang Liu <jiang.liu@linux.intel.com>
+ * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
+ *
+ * Maintained by: <tpmdd-devel@lists.sourceforge.net>
+ *
+ * This file contains implementation of the sysfs interface for PPI.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+
  #include <linux/acpi.h>
  #include "tpm.h"

@@ -22,45 +41,22 @@ static const u8 tpm_ppi_uuid[] = {
  	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
  };

-static char tpm_ppi_version[PPI_VERSION_LEN + 1];
-static acpi_handle tpm_ppi_handle;
-
-static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
-				void **return_value)
-{
-	union acpi_object *obj;
-
-	if (!acpi_check_dsm(handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
-			    1 << TPM_PPI_FN_VERSION))
-		return AE_OK;
-
-	/* Cache version string */
-	obj = acpi_evaluate_dsm_typed(handle, tpm_ppi_uuid,
-				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
-				      NULL, ACPI_TYPE_STRING);
-	if (obj) {
-		strlcpy(tpm_ppi_version, obj->string.pointer,
-			PPI_VERSION_LEN + 1);
-		ACPI_FREE(obj);
-	}
-
-	*return_value = handle;
-
-	return AE_CTRL_TERMINATE;
-}
-
  static inline union acpi_object *
-tpm_eval_dsm(int func, acpi_object_type type, union acpi_object *argv4)
+tpm_eval_dsm(acpi_handle dev_handle, int func, acpi_object_type type,
+	     union acpi_object *argv4)
  {
-	BUG_ON(!tpm_ppi_handle);
-	return acpi_evaluate_dsm_typed(tpm_ppi_handle, tpm_ppi_uuid,
-				       TPM_PPI_REVISION_ID, func, argv4, type);
+	BUG_ON(!dev_handle);
+	return acpi_evaluate_dsm_typed(dev_handle, tpm_ppi_uuid,
+				       TPM_PPI_REVISION_ID,
+				       func, argv4, type);
  }

  static ssize_t tpm_show_ppi_version(struct device *dev,
  				    struct device_attribute *attr, char *buf)
  {
-	return scnprintf(buf, PAGE_SIZE, "%s\n", tpm_ppi_version);
+	struct tpm_chip *chip = dev_get_drvdata(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%s\n", chip->ppi_version);
  }

  static ssize_t tpm_show_ppi_request(struct device *dev,

@@ -68,8 +64,10 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
  {
  	ssize_t size = -EINVAL;
  	union acpi_object *obj;
+	struct tpm_chip *chip = dev_get_drvdata(dev);

-	obj = tpm_eval_dsm(TPM_PPI_FN_GETREQ, ACPI_TYPE_PACKAGE, NULL);
+	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETREQ,
+			   ACPI_TYPE_PACKAGE, NULL);
  	if (!obj)
  		return -ENXIO;

@@ -103,14 +101,15 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
  	int func = TPM_PPI_FN_SUBREQ;
  	union acpi_object *obj, tmp;
  	union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
+	struct tpm_chip *chip = dev_get_drvdata(dev);

  	/*
  	 * the function to submit TPM operation request to pre-os environment
  	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
  	 * version 1.1
  	 */
-	if (acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
-			   1 << TPM_PPI_FN_SUBREQ2))
+	if (acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
+			   TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_SUBREQ2))
  		func = TPM_PPI_FN_SUBREQ2;

  	/*

@@ -119,7 +118,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
  	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
  	 * for compatibility, and use package type since 1.2 according to spec.
  	 */
-	if (strcmp(tpm_ppi_version, "1.2") < 0) {
+	if (strcmp(chip->ppi_version, "1.2") < 0) {
  		if (sscanf(buf, "%d", &req) != 1)
  			return -EINVAL;
  		argv4.type = ACPI_TYPE_BUFFER;

@@ -131,7 +130,8 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
  			return -EINVAL;
  	}

-	obj = tpm_eval_dsm(func, ACPI_TYPE_INTEGER, &argv4);
+	obj = tpm_eval_dsm(chip->acpi_dev_handle, func, ACPI_TYPE_INTEGER,
+			   &argv4);
  	if (!obj) {
  		return -ENXIO;
  	} else {

@@ -157,6 +157,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
  		.buffer.length = 0,
  		.buffer.pointer = NULL
  	};
+	struct tpm_chip *chip = dev_get_drvdata(dev);

  	static char *info[] = {
  		"None",

@@ -171,9 +172,10 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
  	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
  	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
  	 */
-	if (strcmp(tpm_ppi_version, "1.2") < 0)
+	if (strcmp(chip->ppi_version, "1.2") < 0)
  		obj = &tmp;
-	obj = tpm_eval_dsm(TPM_PPI_FN_GETACT, ACPI_TYPE_INTEGER, obj);
+	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETACT,
+			   ACPI_TYPE_INTEGER, obj);
  	if (!obj) {
  		return -ENXIO;
  	} else {

@@ -196,8 +198,10 @@ static ssize_t tpm_show_ppi_response(struct device *dev,
  	acpi_status status = -EINVAL;
  	union acpi_object *obj, *ret_obj;
  	u64 req, res;
+	struct tpm_chip *chip = dev_get_drvdata(dev);

-	obj = tpm_eval_dsm(TPM_PPI_FN_GETRSP, ACPI_TYPE_PACKAGE, NULL);
+	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETRSP,
+			   ACPI_TYPE_PACKAGE, NULL);
  	if (!obj)
  		return -ENXIO;

@@ -248,7 +252,8 @@ cleanup:
  	return status;
  }

-static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
+static ssize_t show_ppi_operations(acpi_handle dev_handle, char *buf, u32 start,
+				   u32 end)
  {
  	int i;
  	u32 ret;

@@ -264,14 +269,15 @@ static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
  		"User not required",
  	};

-	if (!acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
+	if (!acpi_check_dsm(dev_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
  			    1 << TPM_PPI_FN_GETOPR))
  		return -EPERM;

  	tmp.integer.type = ACPI_TYPE_INTEGER;
  	for (i = start; i <= end; i++) {
  		tmp.integer.value = i;
-		obj = tpm_eval_dsm(TPM_PPI_FN_GETOPR, ACPI_TYPE_INTEGER, &argv);
+		obj = tpm_eval_dsm(dev_handle, TPM_PPI_FN_GETOPR,
+				   ACPI_TYPE_INTEGER, &argv);
  		if (!obj) {
  			return -ENOMEM;
  		} else {

@@ -291,14 +297,20 @@ static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
  					   struct device_attribute *attr,
  					   char *buf)
  {
-	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
+	struct tpm_chip *chip = dev_get_drvdata(dev);
+
+	return show_ppi_operations(chip->acpi_dev_handle, buf, 0,
+				   PPI_TPM_REQ_MAX);
  }

  static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
  					  struct device_attribute *attr,
  					  char *buf)
  {
-	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
+	struct tpm_chip *chip = dev_get_drvdata(dev);
+
+	return show_ppi_operations(chip->acpi_dev_handle, buf, PPI_VS_REQ_START,
+				   PPI_VS_REQ_END);
  }

  static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);

@@ -323,16 +335,34 @@ static struct attribute_group ppi_attr_grp = {
  	.attrs = ppi_attrs
  };

-int tpm_add_ppi(struct kobject *parent)
+int tpm_add_ppi(struct tpm_chip *chip)
  {
-	/* Cache TPM ACPI handle and version string */
-	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
-			    ppi_callback, NULL, NULL, &tpm_ppi_handle);
-	return tpm_ppi_handle ? sysfs_create_group(parent, &ppi_attr_grp) : 0;
+	union acpi_object *obj;
+
+	if (!chip->acpi_dev_handle)
+		return 0;
+
+	if (!acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
+			    TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_VERSION))
+		return 0;
+
+	/* Cache PPI version string. */
+	obj = acpi_evaluate_dsm_typed(chip->acpi_dev_handle, tpm_ppi_uuid,
+				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
+				      NULL, ACPI_TYPE_STRING);
+	if (!obj)
+		return -ENOMEM;
+
+	strlcpy(chip->ppi_version, obj->string.pointer,
+		PPI_VERSION_LEN + 1);